// From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys
if (!Object.keys) {
  Object.keys = (function () {
    'use strict';
    var hasOwnProperty = Object.prototype.hasOwnProperty,
        hasDontEnumBug = !({toString: null}).propertyIsEnumerable('toString'),
        dontEnums = [
          'toString',
          'toLocaleString',
          'valueOf',
          'hasOwnProperty',
          'isPrototypeOf',
          'propertyIsEnumerable',
          'constructor'
        ],
        dontEnumsLength = dontEnums.length;

    return function (obj) {
      if (typeof obj !== 'object' && (typeof obj !== 'function' || obj === null)) {
        throw new TypeError('Object.keys called on non-object');
      }

      var result = [], prop, i;

      for (prop in obj) {
        if (hasOwnProperty.call(obj, prop)) {
          result.push(prop);
        }
      }

      if (hasDontEnumBug) {
        for (i = 0; i < dontEnumsLength; i++) {
          if (hasOwnProperty.call(obj, dontEnums[i])) {
            result.push(dontEnums[i]);
          }
        }
      }
      return result;
    };
  }());
}

//Production steps of ECMA-262, Edition 5, 15.4.4.18
//Reference: http://es5.github.com/#x15.4.4.18
if (!Array.prototype.forEach) {

Array.prototype.forEach = function (callback, thisArg) {

 var T, k;

 if (this == null) {
   throw new TypeError(" this is null or not defined");
 }

 // 1. Let O be the result of calling ToObject passing the |this| value as the argument.
 var O = Object(this);

 // 2. Let lenValue be the result of calling the Get internal method of O with the argument "length".
 // 3. Let len be ToUint32(lenValue).
 var len = O.length >>> 0;

 // 4. If IsCallable(callback) is false, throw a TypeError exception.
 // See: http://es5.github.com/#x9.11
 if (typeof callback !== "function") {
   throw new TypeError(callback + " is not a function");
 }

 // 5. If thisArg was supplied, let T be thisArg; else let T be undefined.
 if (arguments.length > 1) {
   T = thisArg;
 }

 // 6. Let k be 0
 k = 0;

 // 7. Repeat, while k < len
 while (k < len) {

   var kValue;

   // a. Let Pk be ToString(k).
   //   This is implicit for LHS operands of the in operator
   // b. Let kPresent be the result of calling the HasProperty internal method of O with argument Pk.
   //   This step can be combined with c
   // c. If kPresent is true, then
   if (k in O) {

     // i. Let kValue be the result of calling the Get internal method of O with argument Pk.
     kValue = O[k];

     // ii. Call the Call internal method of callback with T as the this value and
     // argument list containing kValue, k, and O.
     callback.call(T, kValue, k, O);
   }
   // d. Increase k by 1.
   k++;
 }
 // 8. return undefined
};
}
